Electricity generating fuel cell stacks are typically fueled by hydrogen-rich fuel gases which are synthesized in the fuel cell power plant system by catalytically reforming a raw hydrocarbon fuel. The raw fuel is passed through a catalyst bed which is heated and the resultant gas evolved by the catalyst bed is the hydrogen-rich fuel gas suitable for fueling fuel cell power plants. Ordinarily, the catalyst bed is formed by a plurality of elongated, parallel tubes which are disposed in a reformer housing and which contain the catalyst. The tubes are heated by a burner or the like associated with the reformer housing, and the raw fuel is fed into one end of the tubes with the reformed fuel gas emerging from the tubes. The aforesaid reformer construction is perfectly acceptable for larger fuel cell power plants of the type which will provide electrical power for a building, or which will be used to provide line power by an electric utility. There are, however, fuel cell power applications in which the parallel tube reformer construction is not satisfactory.
These are situations where the power plant must be relatively compact, as, for example, in a vehicle, trailor, portable generator or the like. When such compactness is a requirement, the conventional parallel tube reformers have been found to be inefficient with respect to heat utilization. They have been found to suffer from hot and cold spots to the extent that the operating temperatures must be raised to levels which are deleterious to the catalyst over extended periods of time.